This invention relates to a novel aluminum brazing sheet and a brazing method utilizing such sheet.
It is common practice to join aluminum components by disposing an aluminum brazing alloy between or adjacent the component surfaces to be joined, and heating the brazing alloy and the joining surfaces in appropriately assembled fashion to a temperature (brazing temperature) at which the brazing alloy melts while the components remain unmelted. Upon subsequent cooling, the brazing alloy forms a filet or joint that bonds the joining surfaces of the components. For assured selective melting of only the brazing alloy in the heating step, it is commonly preferred that the melting point of the brazing alloy be at least 30 to 40.degree. C. lower than that of the metal of the components. An example of a typical aluminum brazing alloy is an aluminum-silicon eutectic composition, which starts to melt at about 577.degree. C.
A brazing sheet is commonly prepared by cladding a core aluminum alloy sheet on one of both faces with a sheet of the aluminum brazing alloy. The core alloy is typically an aluminum alloy containing magnesium, e.g. AA 6951, X800, etc. but strong alloys such as AA 6061 are preferred. The typical brazing alloy for the cladding contains about 7.5 to 15% silicon, and usually contains about 12% silicon. This high silicon alloy is relatively expensive to produce and scrap recovery procedures are difficult and expensive.
It is the object of the present invention to produce a brazing sheet which is less expensive to produce and much easier to recover as scrap than is traditional brazing sheet. Another object of the invention is to make a strong brazing sheet using AA6061 as the core material.